Jul. 29, 2024
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Full Port Gate Valves?
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(Petroleum)
(OP)
28 Mar 06 10:22I'm a piping designer with afew years of experience, I was doing a project where the engineer wanted to hot tap thur a 4" valve into a 6" line (this is hydrocarbon service). I normally like to use full port ball valves for this but the engineer indicated he want to use a gate valve to save money. I've run across this before so nothing new. As I was filling out the material requisition I had noted that we needed "full port" gate valves to do this hot tap. My boss saw this and said "ALL" gate valves are "full port" regardless, and didn't need to be indicated! ...News to me, But to be honest I really don't know! I've sent to some major valve manufactures, but they ALL seems to be too busy to answer my question. Can ANYBODY help me here!!?? THX! ...Mark
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(Petroleum)
28 Mar 06 10:37Your boss may be stating an industry "truism". That is, unless otherwise stated, people in the industry assumes certain things due to regular industry "commoness".To my experience, gate valves are usually always "full port". Gate valves are usually only used in on/off service (they are either open or closed), and a full port gives the least pressure lost.In the case of a slab gate (through conduit?), I suppose you can have a hole that is not "full port", although I don't know why one would do that, and I haven't seen one.In my opionion, it doesn't hurt to state full port gate.Many "oldtimeers" sort of "sneer" at this as something an inexperienced person does. I don't share that opinion. There are lots of people in my industry now that could benefit from having the obvious stated.
"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
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(Petroleum)
29 Mar 06 14:2311Echo,
With all due respect to Ashereng, I have to disagree with his comment. Full Port Gate valves are not the norm/standard. Full Port valves are more expensive than Conventional Port, thus the one reason they are not the norm.
I would suggest you contact your valve supplier and get his input. Find out what they normally supply your company, and just to be safe, put "Full Port" on your MR.
Good Luck!
Hench
(Mechanical)
29 Mar 06 15:32Mark-My experience agrees with Hench's. I'd suggest looking at some valve catalogs such as one from Edward Vogt at http://fcd.flowserve.com/valves/documents/Vogt/VVACT-Gate.pdf . Print out the dimension sheet for CL-150 gate valves (page 5 of the .pdf) and toss it on your boss' desk. Ask him what exactly dimension D, the seat diameter, means. For a 4" valve it's listed as 2.75" which I suspect does not fall into his definition of "full port". What I've seen in my industry (petroleum refining) is that larger valves tend to be full port while smaller valves tend to be reduced port. For a hot tap, it's best to just be sure and specify "full port".jt
(Petroleum)
29 Mar 06 16:44Hench, jte,You are correct. I took a look at Flowserve's documents, and they do reference conventional AND full port.I have talked to my colleagues, and they, as myself, are surprised by this. We are currently looking into it more. This is great - I will learn another new thing today.
"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?
(Petroleum)
29 Mar 06 17:47Well... I am chalking this up to one of those regional industry truisms.Evidently, I (and 11echo's boss I guess) come from an area/industry where we only use full port gate valves, even though evidently, reduced port is more commonly used elsewhere.I called Flowserve USA, and they confirm that they sell a whole bunch of conventional port gate valves into the oil and gas industry.I will have to be more diligent in the future when I fill out my gate valve datasheets.Thanks to Hench and jte. It is greatly appreciated. Stars to you guys.
"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?
(Petroleum)
(OP)
30 Mar 06 15:20I want to thank ALL participating authors here. I in deed marched into my boss office and "showed" him a copy of these data sheets! ...He hmmm'd and haaa'd abit but finally bowed to my newly found knowledge. Only thing that would have made it better if he was an a$$, but normally he's a nice guy, so didn't want to "rub it in" too much! *G*
THX for the brownie points!!! ...Mark
(Mechanical)
8 Aug 06 19:18Maybe someone will add some discussion here as to why some gates are standard and other full.
Seems to me that probably they both have same bodies whether cast or forged, same bonnets, stems, packing ... whatever.
Also, are ports same size among all manufactured brands as per API, ASME standards?
I can see that full would have slightly enlarged bore, but am not sure if the pre-machined disc blank could not be the same part for both port types.
So, what is the basic advantage of buying standard rather than full port valve? Can whatever cost savings for standard ports be really significant?
Another question:
Please compare the Classes such as 150, 300, 600, 800, 900, , , as opposed to ANSI Classes such as , , and . (Of course, pressures would be temperature dependant for any material) but what engendered such oddly numbered classes? They do not seem to have an evenly numbered metric correlation. So, is it some historical consideration associated with a particular industry?
2
NozzleTwister(Mechanical)
10 Aug 06 13:38shopper,Refer to the following standards for the minimum port openings allowed:For valves manufactured to API 600 (generally cast valves, flanged and butt-weld, like is made by Crane Valve)API 600, Sect. 5.3.3.1, Table 4, Minimum Port Diameters.For valves manufactured to ANSI/API 602 (generally small forged valves, threaded, socket-weld and flanged, like is made by Vogt)ANSI/API 602, Sect. 5.2, Table 1, Minimum Diameter of Equivalent Flow Passageway.Generally, for forged valves per API 602, a standard port is a reduced port. As well as system block valves, these valves also include vents, drains and instrument connections. As far as system block valves are concerned, they are usually 2" and below for forged and for pipe sizes this small, pressure drop is usually not a problem. And yes, cost is a big factor; a forged full port valve body is the body for the next valve size up. The valve weight and cost can be double or triple.For cast valves per API 600, the minimum port allowed is considered to be full port.Note that 'full port' really means 'considered as full port for flow calculations'. Full port does not mean full size un-obstructed bore. Although the minimum bores are established in the standards noted above, the actual bore diameter will vary from manufacturer to manufacturer.If you need a straight through bore of a certain diameter (for hot-tapping for example) you need to be specific about that in your purchase specifications and verify that on your approval and certified drawings. Don't trust catalog info, some major valve companies contract with valve manufacturers all over the world so the valve you get might not match the one shown in the catalog but it should meet all of the standards and specifications.I hope this helps
If you are looking for more details, kindly visit flow control gate.
NozzleTwister
Houston, Texas
(Industrial)
11 Aug 06 16:52.... While I have over 25 years in the valve distribution industry, I would never consider myself an expert. My experience is that even when a manufacturer presents the valve as "full port" it may not be suitable for hot-tap applications. In the wedge style gate valve, the seat rings are angled to match the wedge disc. While the outside edge of the seat ring may match the "full bore" of the valve body, the lower inside mating surface of the seat is may protrude into the flow path. Using a full bore tap will damage this lower portion of the seat ring, and compromise the sealing surface between the wedge and seat.
That is not much of a technical description, but I hope you get the picture. I have also seen valves with a screwed-in seat ring, with lugs protruding into the bore. When in doubt, insist the valves be examined by a reputable valve service facility - this precaution up front will save a lot of headaches later.
(Mechanical)
16 Aug 06 17:40I always thought gates were full port. But then I always bought the flanged cast iron gates mainly in the 4" and larger range. But it is always good to mention to the supplier that this valve is for a hot tap.
Also, the take-off for a gate valve can be considerably less than a ball valve when you are talking in the 4" range. And with a threaded valve, you run the risk of someone unsrcewing the valve from the main while trying to take the hot-tapper apart.
(Petroleum)
17 Aug 06 12:30mizzoueng,You are not alone. We here have also thought that.I guess that's why I participate in Eng-Tips.
"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
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Facilities typically schedule outages, turnarounds or shutdowns to repair or replace equipment like control valves. They coordinate these scheduled shutdowns to allow for preventative maintenance (PM). During this time, the facility removes the control valves to allow for the inspection and evaluation of potential damage or issues.
The PM may require certain control valves to be evaluated for repair at certain frequencies (annually, bi-annually, etc.), whether there are any known issues or not. In addition, any identified "troublesome" valves, will be pulled for evaluation. The time frame for being shut down can range from days to weeks or a month. It is vital, from a profitability aspect, to have the process go smoothly and everything be up and running on time.
The potential for risk is great during the process of repairing control valves. Risks may include:
Once "non-essential" and "essential" businesses, as classified by the COVID-19 crisis, return to full production, there could be additional risks, such as backlogs on parts and service from manufacturers. Because of the increase in demand, there could be a shortage of skilled labor available to do this work. This will cause delays and possibly even safety risks if "unskilled" labor is used to get the work done. All of these risks can significantly impact the cost of the repair.
Let us look at a hypothetical valve repair. Assume there are 40 control valves requiring repair at an estimated $2,500 per valve. This results in a $100,000 repair quote. The valves will be returned to the facility after being repaired, in partial shipments with a three week promised delivery date. The alternative was to replace all 40 control valves at a known cost of $200,000. The facility decides to save half the cost of buying all new control valves by repairing all of them. This 50% thumb-rule is quite commonly used to determine if a repair or replacement is required. If the cost of repair is less than 50% of replacement cost, the decision might be made to go with repairing the valves. However, the reality is that once the control valves are inspected, the discovery work (additional repairs/parts needed) typically can add an additional 40% to the initial quote. Let's assume a three-day delay; this will cost the facility in overtime paid and production loss. So if we only add a 10% increase to the initial quote due to the delay, the numbers are now 50% more cost which equates to $150,000 versus the initial $100,000 to repair the valves.
So now the hard questions: "Did we really save money?", "Did we start up on time?" and "What was the cost of our lost production?" are being analyzed by the facility. Note that there could be even greater costs due to delays and other factors, again due to the current COVID-19 situation, as previously mentioned.
The advantages of repair by replace are many, given that the real cost may not be that much more than repairing the valves.
Another added benefit could be the ability to upgrade valves&#; positioners to smart digital positioners. This kind of positioner provides diagnostic capabilities that enable predicting maintenance needs. This eliminates the guesswork in determining which control valves to evaluate, saving time, effort and cost.
Another benefit of &#;repair by replace&#; would be the option of upgrading to low-emissions packing to reduce fugitive emissions to the surrounding environment.
Yet another advantage might be to replace valves with different types that still do the job. For example, a reciprocating globe valve could have a drop-in replacement that is a rotary control valve (Figure 3). The replacement valve would offer smaller size, half the weight, lower cost, fewer leakage paths and a smaller number of spare parts.
There are many benefits to repair by replace. This scenario eliminates a significant amount of time, effort and cost that would not be obvious from just looking at the quote for repairing the valves. In addition, the facility will have added value by upgrading the control valves and has the reassurance of a warrantied new control valve to ensure the facilities critical process control is well maintained for years to come. On top of that, this approach means no unplanned downtime and resulting loss of production.
This whole process can be made easier by partnering with control valve experts, such as manufacturers reps. Many stock a comprehensive inventory of control valves, positioners and actuator types and are able to provide the needed configurations. In addition, some offer services to support facility PM shutdowns, including surveying existing valves to determine which need replacement, and repair and/or installation.
During normal times, the cost of repair versus replacement may initially look inviting and seem reasonable. However, during the COVID-19 crisis these are not normal times. Even under ideal conditions, the actual cost of repair frequently exceeds the original estimate and repair always requires the valve be shipped to the repair company. Add to this the complications caused by the pandemic, such as shipping delays and backordered spares, and replacement may be preferable. To make the right decision, pay careful attention to all the factors involved, not just the repair itself. In many cases, the decision to "repair by replace" can significantly reduce a facility&#;s time, effort and costs, especially during the current uncertain business climate.
Jason Ordanoff is business development manager with Eastern Controls Inc. and has over a decade of experience providing control valve solutions to customers in all industries.
From time to time, we are re-posting well-received or particularly valuable articles that have previously run on VALVEMagazine.com so that those who might have missed them will be able to catch up on the best of the best.
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